clang-format: tweak formatting of variable initialization blocks

Summary:
This patch changes the behavior of PenaltyBreakBeforeFirstCallParameter
so that is does not apply after a brace, when Cpp11BracedListStyle is
false.

This way, variable initialization is wrapped more like an initializer
than like a function call, which is more consistent with user
expectations for this braced list style.

With PenaltyBreakBeforeFirstCallParameter=200, this gives the following
code: (with Cpp11BracedListStyle=false)

Before :

  const std::unordered_map<std::string, int> Something::MyHashTable =
      { { "aaaaaaaaaaaaaaaaaaaaa", 0 },
        { "bbbbbbbbbbbbbbbbbbbbb", 1 },
        { "ccccccccccccccccccccc", 2 } };

After :

  const std::unordered_set<std::string> Something::MyUnorderedSet = {
    { "aaaaaaaaaaaaaaaaaaaaa", 0 },
    { "bbbbbbbbbbbbbbbbbbbbb", 1 },
    { "ccccccccccccccccccccc", 2 }
  };

Reviewers: krasimir, djasper, klimek

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D43290

llvm-svn: 332434